HAZARDOUS AREAS - Comparisons Between Standards

The following tables and comments are an attempt to cross reference between different National standards for Hazardous Location Definitions. We note that there is a world wide trend towards IEC standards in the electrical industry and that even the American manufacturers are gearing up to produce products to IEC standards in IEC metric dimensions.

COMPARISON OF ZONES FOR ELECTRICAL EQUIPMENT

IEC/CENELEC/U.K. GERMANY/JAPAN	U.S.A.
ZONE 0	DIVISION 1
ZONE 1	DIVISION 1
ZONE 2	DIVISION 2

COMPARISON OF CLASS II CLASSIFICATIONS - DUSTS

B.S.6467 & A.S. 2236 -CLASS II	U.S.A.-CLASS II
DIP - NO SUB - GROUP	GROUP E - METAL DUSTS
	GROUP F - COAL DUSTS
	GROUP G - GRAIN DUSTS

COMPARISON OF GAS GROUPINGS FOR ELECTRICAL EQUIPMENT

IEC CENELEC AUSTRALIA		U.KBS4683		GERMANY & JAPAN VDEO171 RIIS-TR-TR-79-1		U.S.A. NATIONAL ELECTRIC CODE	Representative Gases
II	IIA	II	IIA	1		D	Propane
	IIB		IIB	2		C	Ethylene
	IIB		IIC	3n	3a	B	Hydrogen
	IIB				3b	None	Carbon Disulphide
	IIB				3c	A	Acetylene

COMPARISON OF ZONES FOR TEMPERATURE CLASSIFICATIONS FOR ELECTRICAL EQUIPMENT.

IEC/CENELEC AUSTRALIA		JAPAN (RIIS - TR - 79 - 1)		U.S.A. (NEC 1984)		MIN IGNITION TEMP DEG C
Class	Maximum Surface Temp. deg.C.	Class	Maximum Surface Temp. deg.C.	Class	Maximum Surface Temp. deg.C.
T1	450	G1	360	T1	450	450
T2	300	G2	240	T2 T2A T2B T2C 2TD	300 280 260 230 215	300 280 260 230 215
T3	200	G3	160	T3 T3A T3B T3C	200 180 165 160	200 180 165 160
T4	135	G4	110	T4 T4A	135 120	135 120
T5	100	G5	80	T5	100	100
T6	85	G6	70	T6	85	85

The tables above are a compilation of information from various sources which we believe to be correct, however, we can accept no responsibility for any inaccuracies.

EXPLOSION PROOF VS FLAMEPROOF

Americans refer to “Explosion Proof”, while the UK and IEC refer to “Flameproof” motors or equipment. In IEC definitions this is an Ex d piece of equipment. Ex d equipment is designed to contain an internal explosion to escape between the “flamepaths”, but cool any flame in the hot gases so that no flames escape from the enclosure to ignite any external flammable gases - hence “Flameproof”.

Although Ex e equipment is designed to be used in a Zone 1 area it cannot be described as “Explosion Proof” or “Flameproof”, as it will not contain an explosion if one did occur. Ex e equipment is manufactured to an approved “Explosion Proof Technique”.